mm: memcontrol: pull the NULL check from __mem_cgroup_same_or_subtree()
The NULL in mm_match_cgroup() comes from a possibly exiting mm->owner. It
makes a lot more sense to check where it's looked up, rather than check
for it in __mem_cgroup_same_or_subtree() where it's unexpected.
No other callsite passes NULL to __mem_cgroup_same_or_subtree().
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index ea00761..e32ab94 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -83,11 +83,12 @@
bool mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *memcg)
{
struct mem_cgroup *task_memcg;
- bool match;
+ bool match = false;
rcu_read_lock();
task_memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
- match = __mem_cgroup_same_or_subtree(memcg, task_memcg);
+ if (task_memcg)
+ match = __mem_cgroup_same_or_subtree(memcg, task_memcg);
rcu_read_unlock();
return match;
}